As is known, boards for gliding over snow have different structures in order to meet a variety of criteria, in particular of performance and response. Thus, a first family of boards is known whose structure consists of a stack of successive layers, namely a sole and edges intended to come into contact with the snow, a core constituting the heart of the ski, reinforcements, and an upper assembly supporting the trim.
As is known, the core is generally bordered by reinforcing elements present over the entire length of the ski, or more precisely over all of its running length, that is to say the length of the ski lying between the front and rear contact lines. Such reinforcing elements can be seen on the sides of the ski. These reinforcing elements are used as components for transmitting forces from the upper face of the ski to the edges. In this way, the forces exerted by the skier, in particular in the turn initiation phase, are efficiently transmitted to the edges. A "sandwich" structure of this type therefore has a certain flexibility with specific features imparted by the shear effect generated between the layers when the ski bends.
Skis produced with this structure are particularly efficient at high speed because they maintain optimum contact with the snow. These skis are therefore accurate and fast, albeit somewhat difficult to steer under certain run and snow conditions.
Further, another type of structure, commonly referred to as the "box" structure, consists in covering at least a portion of the core with a reinforcement fabric, this type of tubular reinforcing being different from the laminar reinforcing in the previous structure.
Skis produced with this "box" structure are torsionally stronger. They make it possible to set the edges more efficiently, and therefore allow better accuracy during turns.
A variant of this "box" structure is commonly referred to as a "shell" structure. Such a gliding board has edges which are free from extra longitudinal reinforcing elements.
In such a structure, the upper reinforcement layer is laterally extended within the sides until it comes close to the edges. The lack of a longitudinal reinforcing element in the sides makes such a board weaker in terms of bearing strength on the edge. Such a ski is therefore less reactive and facilitates more comfortable and more forgiving skiing. Side slipping is thus easier to perform with this "shell" structure.
Further, from the Applicant's Patent FR 2 703 916 corresponding to U.S. Pat. No. 5,553,884, a ski is also known which combines, over a portion of its length, a "shell" upper structure and, over the lower portion, a "sandwich" structure including reinforcing elements located at the sides, and supporting said shell.
In practice, although satisfactory, such a ski has mediocre qualities in terms of torsional rigidity and capability, which correspond neither to the highly responsive nature of a stacked structure nor to the forgiving nature of a pure "shell" structure.